/*
 * Copyright (c) 2011 Salzburg Research.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package at.newmedialab.ldpath.backend.linkeddata;

import at.newmedialab.ldclient.model.CacheEntry;
import org.openrdf.repository.Repository;
import org.openrdf.repository.RepositoryException;
import org.openrdf.repository.sail.SailRepository;
import org.openrdf.sail.memory.MemoryStore;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.util.HashMap;
import java.util.Map;

/**
 * A Linked Data backend implementation with no persistent storage. All retrieved data is kept in memory and discarded
 * when the virtual machine exits.
 * <p/>
 * Author: Sebastian Schaffert
 */
public class LDMemoryBackend extends AbstractLDBackend {

    private static final Logger log = LoggerFactory.getLogger(LDMemoryBackend.class);

    private Map<String,CacheEntry> cacheEntries;

    public LDMemoryBackend() {
        super();

        cacheEntries = new HashMap<String,CacheEntry>();

        try {
            Repository repository = new SailRepository(new MemoryStore());
            repository.initialize();
            setRepository(repository);

        } catch (RepositoryException e) {
            log.error("error initialising connection to Sesame in-memory repository",e);
        }

    }



    /**
     * Return a map that can be used to store caching metadata about resources. The LDCacheProvider should take care
     * of persisting the metadata if desired.
     *
     * @return a map for storing caching metadata
     */
    @Override
    public Map<String,CacheEntry> getMetadataRepository() {
        return cacheEntries;
    }

}
